Control moment gyroscope arrays, reaction wheel arrays, and other such devices deployed onboard spacecraft for attitude adjustment purposes generate vibratory forces during operation. Vibration isolation systems are commonly employed to minimize the transmission of vibratory forces emitted from such attitude adjustment devices, through the spacecraft body, to any vibration-sensitive components (e.g., optical payloads) carried by the spacecraft. Vibration isolation systems commonly include a number of individual vibration isolators (typically three to eight isolators), which are positioned between the spacecraft payload and the spacecraft body in a multi-point mounting arrangement. The performance of a vibration isolation systems is largely determined by the number of isolators included within the system, the manner in which the isolators are arranged, and the vibration attenuation characteristics of each individual isolator. Vibration isolation system employing three parameter isolators, which behave mechanically as a main spring in parallel with a series-coupled secondary spring and damper, provide superior attenuation of high frequency vibratory forces (commonly referred to as “jitter”) as compared to vibration isolation systems employing other types of passive isolators, such as viscoelastic isolators. The three parameter isolators are advantageously implemented as single degree of freedom (“DOF”) devices, which provide damping along a single longitudinal axis. An example of a single DOF, three parameter isolator is the D-STRUT® isolator developed and commercially marketed by Honeywell, Inc., currently headquartered in Morristown, N.J.
As noted above, three parameter isolators are commonly designed as single DOF devices. As such, lateral disturbance forces resulting from random vibrations, lateral impacts, or other environmental sources can induce undesired bending modes in the isolator. In many cases, the lateral disturbance forces are minimal and the bending modes are non-problematic or can be addressed by reducing the input forces applied to the isolator. When this is not the case, however, bending modes can occur within the isolator sufficient to induce significant off-axis motion (e.g., lateral and rotational displacements about axes orthogonal to the working axis) in the main spring and other isolator components. Such lateral and rotational displacements can subject the isolator components to undesirably high mechanical stress and rapid fatigue. This can be particularly problematic when the lateral modes are encountered at or near frequencies of particular sensitivity to mission requirements. While the isolator components can be produced to have a greater structural robustness, this typically requires a heavier, bulkier design unfavorable to many airborne and spaceborne applications.
It is thus desirable to provide embodiments of a single-DOF, axial damping isolator, such as a three parameter isolator, having an increased resistivity to off axis motion and, especially, lateral bending modes occurring at lower frequencies at which isolators commonly operate. Ideally, embodiments of such an isolator would be relatively straightforward to manufacture, compact, and lightweight. Other desirable features and characteristics of the present invention will become apparent from the subsequent Detailed Description and the appended Claims, taken in conjunction with the accompanying Drawings and the foregoing Background.